Design and comparison of MHEMT and diode based K-band sub-harmonically pumped mixer MMICs

This paper presents the design, simulation and measured results of two types of K-band monolithic sub-harmonically pumped (SHP) mixers. The mixers are designed using 0.13um metamorphic high electron mobility transistor (mHEMT) process from OMMIC foundry. In this paper, performances of mHEMT based SHP resistive mixer and anti-parallel diode pair based SHP mixer are compared. In both the designs radio frequency (RF) filter, intermediate frequency (IF) filter and local oscillator (LO) balun are kept same for rational comparison. Chip size is 2.35mm × 1.74mm for both the mixers. Measured (on-wafer) conversion loss for mHEMT based SHP resistive mixer is 8.2dB and it is 9.4dB for anti-parallel diode pair based SHP mixer. MHEMT based SHP resistive mixer is found better in performance for conversion loss and input 1dB compression point. However, anti-parallel diode pair based SHP mixer is much superior in rejection of second harmonic of LO. These circuits are realized for S-band (2-3 GHz) to K-band (20-22 GHz) on-board satellite up-converter.